Rotating fin

ABSTRACT

A rotatable sleeve with attached clipped double delta shaped fins for mounting on a missile body so that the fins may achieve a position of symmetry with respect to incident air flow thereon without spinning-up.

United States Ratent [191 Peoples Feb. 5, 11.974

[ 1 ROTATING FIN [75] Inventor: John R. Peoples, China Lake, Calif.

[73] Assignee: The United States of America as represented by theSecretary of the Navy, Washington, DC.

[22] Filed: Aug. 21, 1972 [21] Appl. No.: 282,525

Related U.S. Application Data [63] Continuation-impart of Ser, No.118,266, Feb. 24,

I971, abandoned.

[52] U.S. Cl. 244/323 [51] Int. Cl. F42b 15/14 [58] Field of Search102/34.1, 37.1, 3;

[56] References Cited UNITED STATES PATENTS l/l96l Strickland et al244/323 X 4/1968 Oss et a]. 244/3.24 5/1964 Hall 244/315 X 3,223,03412/1965 Robertson 244/324 3,236,182 2/1966 Dahm 244/324 OTHERPUBLICATIONS Fuller, Dennis E. and G. J. Foster, N.A.S.A. Technical NoteD-l929, Aerodynamic Characteristics of Rocket Vehicle Configurations,Langley Research Center, Hampton, Va., May 6, 1963.

Yuska, Joseph A, N.A.S.A. Technical Note D-3l82, AerodynamicCharacteristics of Rocket Vehicle with Thick Wedge Fins and SweptbackEdges, Lewis Research Center, Cleve. Ohio, Oct. 4, 1965 PrimaryExaminer-Verlin R. Pendegrass Attorney, Agent, or FirmR. S. Sciascia;Roy Miller; R. F. Beers [5 7] ABSTRACT A rotatable sleeve with attachedclipped double delta shaped fins for mounting on a missile body so thatthe fins may achieve a position of symmetry with respect to incident airflow thereon without spinning-up.

2 la m 7 Draw eaEi u s.

sgii'smos PATENIEUFEB 5 1974 smmmz 22 O-NuII Points FIG. 4.

TORQUE INVENTOR.

JOHN R. PEOPLES BY: RoY MILLER ATTOR N EY.

PATENTEDFEB 5 1974 Fig. 5

Fig. 7

Fig.6

ROTATING FIN CROSS-REFERENCE TO RELATED APPLICATIONS:

This application is a continuation-in-part of Ser. No. 118,266 filedFeb. 24, 1971, and now abandoned.

BACKGROUND OF THE INVENTION A recurrent problem in guided missiles isthat of induced roll coupling. Induced roll coupling is caused by thetorque induced by the change in air flow over the fins of a guidedmissile accompanying a turning maneuver.

When a missile is at an angle of attack the forces due to incident airflow on one side of the missile are greater than on the other side.Unless the fixed fins of the missile are at a null position, rollcoupling will be induced. The present invention obviates the problem ofroll coupling by providing the missile fins with means to achieve aposition of symmetry, i.e., a null position, with respect to theincident air flow.

SUMMARY OF THE INVENTION The present invention obviates problemsincident to induced roll coupling. The invention comprises mounting theaft fins on a missile such as Sidewinder on a sleeve which is free torotate about the missile axis. The sleeve is supported on bearings foreand aft and is free to rotate under the force induced on the finsmounted on the sleeve. The fins are of a clipped double deltaconfiguration so that the fins and sleeve do not spin-up under the forceinduced by the change in air flow accompanying a tunring maneuver.Instead, the fins are allowed to, and do achieve, a position of symmetryi.e., a null position with respect to the incident air flow.

DESCRIPTION OF THE DRAWING FIG. 1 is an elevational view of theinvention in cross section as it appears on a guided missile;

FIG. 2 is an elevational view of a back of the missile in one of itsnull positions;

FIG. 3 is an elevational view of a back of the missile in the other ofits null positions;

FIG. 4 is a graph of torque caused by induced roll coupling versus theangle between a null position of the fins and a non null position of thefins for a four fin sleeve;

FIG. 5 is a plan view of the invention;

FIG. 6 is a side elevation view of the invention; and

FIG. 7 is an elevation view of the back end of the fin.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 shows a missile 10 withstabilizing fins 12 connected to the missile by a rotatable sleeve 14.The sleeve is supported on bearings 16 fore and aft and is free torotate under the force induced on the fins mounted on the sleeve. FIG. 1shows the missile turning in the direction of arrow 18 causing theincident air flow 20 to be greater on the lower side of the fins than onthe upper side. It is seen in FIGS. 2 and 3 that when the missile is ina turn as shown in FIG. 1, there is greater air flow over the bottomportions of the fins. If the fins are at an angle 4) to the nullposition of FIGS. 2 and 3, one of the bottom fins will display a greaterarea with respect to the incident air flow than will the other fin. Thiswill cause a missile with nonrotatable fins to spin in the direction ofarrows 22.

The guidance system of the missile is unable to react quickly enough tocause the swivel nozzle to move quickly enough to compensate for thisspin. The missile will thus veer off in a wrong direction.

The present invention obviates this problem incident to induced rollcoupling. The sleeve is free to rotate under the force induced on thefin mounted on the sleeve. The fins are so shaped that the fins andsleeve do not spin under the force induced by the change in air flowaccompanying a turning maneuver. Instead, the fins achieve a position ofsymmetry with respect to the incident air flow, that is, a nullposition. It is to be noted that a four fin rotatable sleeve will neverrotate more than 22/2 to achieve a null position; an eight fin sleevenot more than 11 1/4", etc.

Fin 12 of FIG. 1 is shown in greater detail in FIGS. 5, 6 and 7. It isseen that the fin is of a clipped double delta configuration. Theperimeter of the fin from point 28 to point 30 is rounded off. Theforward portion 24 of the fin becomes increasingly thicker from front toback as does the main portion of the fin from top to bottom with therear edge 26 of the fin being flat.

What is claimed is:

l. A device for obviating induced roll coupling in a guided missilecomprising:

a missile having a generally elongated cylindrical body member forproviding stablized flight;

a plurality of fins mounted to freely revolve transversally in eitherdirection to the longitudinal axis of said missile for allowing saidfins to move during said missile flight;

said fins being streamline shaped members having a base aligned parallelwith the longitudinal axis of said missile body, leading and trailingedges inclined with respect to said base, a tip of shorter axialdimension than said base dimension and spaced a substantial distancefrom said base forming a symmetrical member for aligning itself in theair stream; and

bearing means positioned on the circumference of said missile body andhaving a portion fixably secured to said base for holding said fins inspaced relationship to one another around the circumference of saidmissile body;

whereby the fins rotate with respect to said missile body to seek a nullposition during flight of the missile and rotate to maintain this nullposition during missile turning maneuvers.

2. The device of claim 1 wherein the profile of said fin is tapered fromsaid base to said tip and having a and said tip edge.

1. A device for obviating induced roll coupling in a guided missilecomprising: a missile having a generally elongated cylindrical bodymember for providing stablized flight; a plurality of fins mounted tofreely revolve transversally in either direction to the longitudinalaxis of said missile for allowing said fins to move during said missileflight; said fins being streamline shaped members having a base alignedparallel with the longitudinal axis of said missile body, leading andtrailing edges inclined with respect to said base, a tip of shorteraxial dimension than said base dimension and spaced a substantialdistance from said base forming a symmetrical member for aligning itselfin the air stream; and bearing means positioned on the circumference ofsaid missile body and having a portion fixably secured to said base forholding said fins in spaced relationship to one another around thecircumference of said missile body; whereby the fins rotate with respectto said missile body to seek a null position during flight of themissile and rotate to maintain this null position during missile turningmaneuvers.
 2. The device of claim 1 wherein the profile of said fin istapered from said base to said tip and having a front portion taperedtowards said leading edge from a plane perpendicular to said base andextending through the corner formed by the meeting of said leading edgeand said tip edge.